Embossed curtainwall with overlapped portions



Aug. 26, 1969 H. JAMGOCHIAN 3,452,901

EMBOSSED CURTAINWALL WITH OVERLAPPED PORTIONS Filed July 31, 1967 7Sheets-Sheet 1 INVENTOR HAIGH JAMGOCHIAN 1969 H. JAMGOCHIAN 3,462,961

EMBOSSED CURTAINWALL' WITH OVERLAPPED PORTIONS Filed July 31, 1967 7Sheets-Sheet 2 mft r\ \3;

FIG. 5

INVENTOR HAIGH' JAMGOCHIAN 6, 1969 H. JAMGOCHIAN 3,462,901

Q EMBOSSED GURTAINWALL WITH OVERLAPPED PORTIONS I Filed July 31, .1967 7Sheets-Sheet 5 INVENTOR HAIGH JAMGOCHIAN AGE/VT Aug. 26, 1969 H.JAMGOCHIAN 3,462,901

I EMBOSSED CURTAINWALL WITH OVERLAPPED PORTIONS Filed July 31, 19s? vSheets-Sheet 4 INVENTOR 'HAIGH JAMGOCHIAN AGENT Aug. 26,1969 H.JAMGOCHIAN 3,462,901

EMBOSSED CURTAINWALL WITH OVERLAY-FED PORTIONS Filed July 31, 1967 7Sheets-Sheet 5 m INVENTOR Q). HAIGH JAMGOCHIAN AGENT 26, 1969 H.JAMGOCHIAN 3,462,901

- EMBOSSED CURTAINWALL WITH OVERLAPPED PORTIONS Filed July 31, 1967 '7Sheets-Sheet 6 INVENI'OR HAIGH JAMGOCHIAN BY Q/MWaM gQmz y AGE/VT 1969H. JAMGOCHIAN 3,462,901

EMBOSSED CURTAINWALL wma OVERLAPPED PORTIONS Filed July 31, 1967Sheets-Sheet v FIG. 13

INVENTOR HAIGH JAMGOCHIAN AGENT United States Patent US. Cl. 52-316 9Claims ABSTRACT OF THE DISCLOSURE A long, seamless and jointless sheetmetal strip is employed to fabricate a curtainwall by attaching twospacedapart rows of supporting means to an underlying building structureand fastening the sheet metal strip across these rows of supportingmeans. Tucks are made by folding overlaps at intervals along both edgesof the strip, thereby incorporating excess material in the curtainwallto accommodate expansion and contraction, while continuing to fasten thestrip to the supporting means. Additionally, the sheet metal strip maybe wrinkled purposely at many points between the rows of supportingmeans to increase the curtainWalls stiffness and mechanical stabilitywhile also providing a unique, artistic, textured appearance.

BACKGROUND OF THE INVENTION Curtainwalls and the methods by which theyare fabricated have many variations in conventional practice, but allprior art structures and erection methods known to this inventor have incommon at least two basic similarities, namely: (1) That discretestructural panels and glazing components are employed, and (2) thatexpansion joints of some type must be provided between panels toaccommodate thermal expansion and contraction.

Due to these inescapable needs in prior art curtainwalls for theassembly of discrete modular panels and for the provision of expansionjoints between them, every known curtainwall fabrication method is moreexpensive in terms of materials and hardware and on-site labor coststhan is the method of this invention.

In conventional practice, a curtainwall is usually erected by formingindividual frames from frame members which are attached to an exteriorwall of a building or to the skelton of a building which comprisesvertical columns and horizontal beams. Each individual frame may besupported upon a buildings exterior wall or upon its skeletal frameworkby slidable means in order to accommodate expansion and contraction. Anyframe can receive structural panels, glazing, or other non-load-bearingelements of the curtainwall.

Expansion joints between curtainwall panels are usually madeweatherproof by caulking, installation of compressed resilient elementsand the like, and these exposed joints are finally covered by decorativemullions. Prior to finishing of the expansion joints, each structuralpanel must be individually fastened to the underlying framework.

Such assembly procedures require skilled labor and the rate in linearfeet per minute at which a conventional curtainwall can be constructedis very low.

SUMMARY OF THE INVENTION This invention relates to a pioneering advancein curtainwalls and in methods for employing extremely lightweightmaterials in their construction. The present method teaches how toconstruct an attractive, strong, and mechanically stable curtainwallusing materials never previously employed for this purpose, namely,relatively thin gauge sheet metal of various types and of many widthswhich is available in long seamless and jointless strips 3 ,462,901Patented Aug. 26, 1969 supplied in coils, or pre-creased into accordionfolds and supplied in stacks.

The method of construction and the curtainwall of this inventioncomprehends the attachment of two spaced-apart rows of supporting meansto an underlying framing or wall thereby defining the width, shape,position, and extent of a curtainwall. These spaced rows of supportingmeans can be arranged in two substantially parallel horizontal lines fora horizontal curtainwall or they can be arranged in vertical columns fora vertical curtainwall or in any desired shape or position includingdiverging or converging lines of alternating divergent and convergentshapes.

The underlying building structure to which the rows of supporting meansare attached may be the skeletal frame work of a building comprisinghorizontal beams and vertical columns or it may consist of studdingonly, or it may be an existing wall of a building.

After the width, shape, position, and extent of the curtainwall havebeen established by the attachment of two rows of supporting means to anunderlying building structure, one end of a long sheet metal strip isfastened across said rows of supporting means with the major portion ofthe width of said strip spanning the distance between said rows.

Because the sheet metal employed in the practice of the method of thisinvention is thin enough and of the proper temper to be bendable andfoldable, the problem of providing for thermal expansion and contractionas well as acoustical vibration is solved by bending and folding thesheet metal strip to form tucks by overlapping portions of the strip atintervals along each edge before it is fastened to the corresponding rowof supporting means. It is entirely optional whether or not there is anyregularity to the spacing of the tucks along either edge of the sheetmetal strip. Thus, due to the incorporation of a sufficient amount ofexcess material in the curtainwall by virtue of the tucks or overlaps toaccommodate expansion and contraction in any direction, no expansionjoints are needed and consequently there is a great saving in cost ofconstruction compared with conventional curtainwalls.

When the surface of a curtainwall is canted at an angle to the vertical,as when a wall is tapered, two horizontal rows of supporting meansarranged to provide such a taper will not be the same length. Forexample, the circumference of a tapered wall will increase in thedirection of the increasing taper. In such cases, the total number ofoverlaps or tucks or the aggregate amount of overlap in all tuckscombined will have to be greater at the shorter edge of the sheet metalcurtainwall than along the longer edge in order to use up the excesssheet metal along the shorter edge of the curtainwall.

When such overlaps or tucks are folded and bent into the seamless andjointless metal sheet, protection against inward or outward buckling oroilcanning of the sheet metal is obtained as a by-product of suchbending and folding which necessitates hammering the surface of thesheet. Such hammering or beating of the sheet metalto form the tucksproduces indentations in the sheet metal strip over a wide area. Theseindentations may be completely random or, alternately, may beartistically done to provide a more regular or intentional pattern. Inboth instances, whether the indentations caused in forming tucks areregular or irregular what has, in effect, been created is an irregularsurface which lends great stiffness and resistance to movement ordeformation to a curtainwall and also provides the possibility fororginality in texture effects.

When the tucks formed at intervals along each edge of the sheet metalstrip are large enough to extend nearly to the midpoint of the width ofthe strip or farther, the irregularities in the surface of the stripproduced by these large tucks will be sufficient to impart greatstifiness and stability as well as a desirable textured appearance tothe strip.

However, when the tucks are small and do not extend very far toward themidpoint of the width of the strip, large areas near the midpoint linealong the length of the strip will remain as a smooth metal surfacewhich would oilcan, meaning to deform inward or outward due to theeffects of thermal expansion and contraction or wind loading. Suchoilcanning is not desirable because it is noisy and may cause eventualdestruction of portions of the curtainwall by tearing it loose from itssupports.

Therefore, in the event an architects design calls for small tucks whichdo not provide sufficient irregularities in the sheet metal stripssurface to resist oilcanning, deliberate wrinkling of the strip at aplurality of points intermediate said supports becomes necessary. Suchwrinkling may be accomplished by hammering indentations into either sideof the strip or by embossing a texture or a design into either surfaceof the strip or by other means which produce a sufficient number ofirregularities so that expansion and contraction can occur in anydirection while the overall shape of the curtainwall remains stable.

Accordingly, the method of this invention comprehends the carrying outof an additional step comprising hammering or otherwise wrinkling anylarge smooth area of the sheet metal strip which remains free ofindentations after the steps of tuck formation and attachment of thestrip to the supporting means have been completed.

The wrinkling of any smooth areas remaining then in the sheet metalstrip may also be accomplished by embossing a design in either surfaceof the curtainwall. Thus, an embossing die, which may be a female diecomprising a surface having depressions forming a design therein, may beheld against one side of a curtainwall constructed according to themethod of this invention and hammer blows may be directed against thecorresponding portion of the opposite surface of the curtainwall,forcing the sheet metal into the depressions in the die, thereby forminga depressed replica of the design in the curtainwall.

Alternatively, other desirable artistic effects can be created in thesurface of a curtainwall constructed according to the method of thisinvention by holding a male embossing die having protuberances thereonagainst one side of the sheet metal strip and directing hammer blowsagainst the opposite side of the curtainwall to form a raised replica orrelief corresponding to the design on the male embossing die.

A further alternative is to employ free-hand hammering to produce atextured appearance or any desired artistic effect in the surface of thecurtainwall of this invention.

Thus, the exposed surface of the curtainwall of this invention can bedecorated with a wide range of sculptural effects in either relief orintaglio and such effects can comprise symbols or written characters andwords as well as likenesses of people or objects. The range of choice isinfinite in terms of design possibilities which may render a buildingunique and endow it with the character of a highly individual work ofart.

Practice of the method of this invention has also proved that when soft,zero temper, sheet metal strip is hammered both in forming tucks and indeliberate wrinkling of any remaining smooth areas of the strip, thetemper of the metal is increased by such working and it becomes muchharder, thereby improving the stiffness and mechanical stability of thecurtainwall of this invention.

It should be noted that when the curtainwall of this invention isconstructed on rows of supporting means framework of a building, theinner surface of the curtainwhich have previously been attached to theskeletal wall may be finished, for example, by spraying a thick coatingof urethane foam insulation on it, or by packing fiberglass bats againstit. Drywall or wetwall construction can then be carried out interiorallyof such insulation against the inside of the studding or framework ofthe building.

The steps which must be taken in combination to give the method of thisinvention and which are reflected in the curtainwall which is claimedherein, are:

.(A) attaching two spaced-apart rows of supporting means to anunderlying building structure;

(B) fastening a portion of a long sheet metal strip across said rows ofsupporting means with the major portion of said strip spanning thedistance between said rows;

(C) forming tucks by overlapping portions of said strip at intervalsalong each edge of said strip, while (D) continuing to fasten said stripacross said rows of supporting means at a plurality of points near eachedge of and along the length of said strip.

An additional method step may be necessary in cases where, for a varietyof reasons, the tucks formed along both edges of the sheet metal stripand the concommitant hammering which is usually necessary in bending andfolding these overlaps do nat eliminate all large smooth undisturbedareas from the surface of the curtainwall. In such cases, deliberatewrinkling of such large smooth areas becomes necessary, as previouslydescribed, or, as an alternative procedure, embossing of a design in thecurtainwall eliminates such smooth areas while creating desirabledecorative effects, as has also been previously described.

Nevertheless, the broadest definition of the combination of thisinvention comprises the steps A through D given above, wherein provisionis made for incorporating excess material into a curtainwall so thatexpansion and contraction can occur in any direction, therebyeliminating the need for expensive and time-consuming fabrication ofexpansion joints and permitting very rapid wall erection in a long,unbroken strip at speeds of several feet per minute.

Brief description of the drawing FIGURE 1 is a perspective schematicview showing one alternative modification of the two spaced-apart rowsof supporting means across which a sheet metal strip may be fastenedaccording to the method of this invention.

FIGURE 2 is a partial sectional view on line 11 of FIG. 1.

FIGURE 3 is a perspective schematic view showing a second alternativemodification of the two spaced-apart rows of supporting means acrosswhich a sheet metal strip may be fastened to form the curtainwall ofthis invention.

FIGURE 4 is a partial sectional view on line 33' of FIGURE 3.

FIGURE 5 contains three perspective schematic views, A, B, and C, whichillustrate a third alternative modification of the two spaced-apart rowsof supporting means shown in other modifications in FIGS. 1 through 4,showing how a sheet metal strip may be applied thereto to form acurtainwall according to the method of this invention.

FIGURE 6 contains four perspective schematic views, A, B, C, and D,which illustrate the same modification of the two spaced-apart rows ofsupporting means illustrated in FIG. 5, showing a variation of themethod by which a curtainwall may be constructed according to the methodof this invention.

FIGURE 7 is a perspective schematic view illustrating a finishedcurtainwall constructed according to the method of this invention.

FIGURE 8 is a sectional elevation taken along line 77' of FIG. 7 whichalso contains additional structural details illustrating one way inwhich flashing, roofing, studding, and associated structures relate tothe two rows of supporting means across which the curtainwall of thisinvention is constructed.

FIGURE 9 is a partial sectional schematic elevation through amulti-tiered curtainwall constructed according to the method of thisinvention.

FIGURE 10, views A, B, and C illustrate in perspective schematic threealternative modifications of ways to fasten a sheet metal strip to onerow of supporting means according to the method of this invention, andview D is a partial sectional schematic illustrating a fourthalternative way to fasten the sheet metal strip to a support.

FIGURE 11, contains perspective schematic views A, B, and C whichillustrate how a pre-creased sheet metal strip, provided withpre-determined fold points, may be used to construct a curtainwallaccording to the method of this invention.

FIGURE 12 is a perspective schematic view illustrating a verticalcurtainwall constructed according to the method of this invention acrosstwo vertically disposed rows of supporting means.

FIGURE 13 is an exploded schematic view illustrating a method forembossing a design in the curtainwall of this invention.

Referring now to FIG. 1, structures 2 and 2' are spacedapart wire cablesheld under tension and supported at intervals by clamps 4 which areattached to an underlying building structure 5. Such attachment maycomprise anchoring of clamps 5 to an exterior wall of a buildingundergoing renovation or, alternatively, may comprise bolting, welding,or riveting to the skeletal framework of a building under construction.In either case, the attachment of two rows of supporting means,represented here by cables 2 and 2' to an underlying building structure5 is a first step in constructing the curtainwall of this inventionbecause the spacing of these two rows of supporting means defines thewidth of the curtainwall just as their length and inclination to thevertical define the curtainwalls length and taper. Brackets 6 snap overcables 2 and 2 when these cables are bowed toward each other. Brackets-6 may be spaced every two feet along each cable 2 or 2', for example,and are employed to provide a simple and fast means of fasteningportions of the edges of a sheet metal strip across cables 2 and 2.

Referring to FIG. 2, a portion of a bracket 6 is shown snapped overcable 2 and one edge of a sheet metal strip 8 is shown fastened securelyin bracket 6 by driven wedge 9. The portion of the edge of sheet metalstrip 8 which is bent over cable 2 and wedged into bracket 6 maycomprise a tuck or overlapped portion of one edge of strip 8 or mayalternatively, consist only of a straight portion of one edge of strip8. The edges of strip 8 are folded back over cables 2 and 2 and arecrimped around them in the spaces between brackets t5. It is evenfeasible to eliminate brackets 6 and to crimp both edges of strip 8tightly over cables 2 and 2 throughout their lengths.

In FIG. 3 an alternative modification is shown wherein the twospaced-apart rows of supporting means which are attached to anunderlying building structure to define the length and width of thecurtainwall of this invention, comprise brackets which are anchored tothe underlying building structure 5, which may be a wall or,alternatively, may be the studding or framework of a building.

A typical bracket 10 is shown in FIG. 4 attached to wall 5 by bolt 11,and sheet metal strip 8 is shown bent over the top of bracket 10 andsecured within bracket 10 by wedge 9'.

The modification of the supporting means illustrated in FIGS. 3 and 4 isbest suited to the construction of the curtainwall of this invention onthe exterior wall of a building undergoing renovation because, in such acase, the brackets 10 in either row can be spaced at very closeintervals on the wall, such as on one or two foot centers, to providemany closely spaced points at which each edge of sheet metal strip '8can be fastened.

A still further modification of the two spaced-apart rows of supportingmeans is shown in view A of FIG. 5 wherein two spaced-apart rows offurring strips 12 and 12 are attached to an underlying buildingstructure 5. These may be long rows of furring strips which are boltedto the studding comprising part of the skeletal framework of a buildingduring construction, and the curtainwall of this invention will thencomprise a portion of the outer skin of the building. The method stepwherein these furring strips 12 and 12' are first attached to anunderlying building structure 5 defines the size and position of thecurtainwall.

Subsequently, sheet metal strip 8 is fastened across the two rows ofsupporting means 12 and 12, as is also shown in view A of FIG. 5. Theexact means employed to fasten strip 8 to supporting means 12 and 12 isoptional, and several modifications illustrating difierent ways this maybe accomplished are shown in FIG. 10, views A, B, C, and D, which willbe discussed in more detail below.

View B of FIG. 5 illustrates tucks 13 which have been formed in bothedges of sheet metal strip 8 in order to incorporate excess material inthe curtainwall to provide for thermal expansion and contraction.

While tucks 13 are being formed by bending and folding overlaps in sheetmetal strip 8, the fastening of strip 8 to supporting means 12 and 12'is continued. Thus, both the tuck-forming step and the step of fasteningthe strip 8 across the two spaced-apart tows of supporting means arecarried out more or less concommitantly since some of the constructioncrew members should be hammering and bending the sheet metal to formtucks while other crew members follow them'and fasten both theoverlapped and the straight portions of the strip 8 to the two rows ofsupporting means 12 and 12.

View C of FIG. 5 shows the sheet metal strip 8 as it appears after tucks13 have been formed at intervals along both edges, and after these edgesof strip 8 have been hammered and bent over supporting means 12 and 12'preparatory to fastening with nails 14 (as illustrated) or attachment byany suitable means such as the examples shown in views A, B, C. and D ofFIG. 10.

The tucks 13 formed in one edge of strip 8 need not lie directlyopposite the tucks formed in the opposite edge of strip 8. The spacingof tucks can be irregular. Although the principal purpose of these tucksis to provide the essential function of incorporating needed excessmaterial in the curtainwall to accomodate expansion and contraction, asubsidiary function of these tucks is to provide a way to shorten eitheredge of strip 8 when necessary to keep strip 8 following the two rows ofsupporting means 12 and 12'. Even when these rows of supporting means 12and 12' are parallel, the difficulty in handling a large coil of widesheet metal strip makes it nearly impossible in practice to keep strip 8from cocking at an angle to the rows of supporting means. When thishappens, strip 8 can be brought back into parallel relationship with therows of supporting means by overlapping more material and therebyshortening the edge of strip 8 which is running farthest outside of thearea defined by rows of supporting means 12 and 12, When one row ofsupporting means is shorter or longer than the other, as in a taperedwall, more material must be overlapped and incorporated in tucks alongthe edge of the sheet metal strip which follows the shorter row ofsupporting means.

It should be noted in view C of FIG. 5 that the hammering necessary tobend and form tucks 13 in both edges of strip 8 has resulted in theformation of wrinkles covering most of the surface of strip 8, leavingno large smooth undisturbed areas which could give rise to oilcanning.The reason for this is that tucks 13 are very large and extend from bothedges nearly to the longitudinal mid-line of strip 8 or even farther.Thus, since the formation of these large tucks results in theelimination of substantially all large smooth areas from the sheet metalstrip, no additional step of forming more wrinkles is necessary.

However, referring now to FIG. 6, there is illustrated the case whererelatively small tucks which do not extend anywhere near thelongitudinal midline of strip 8, are formed along both edges of a verywide sheet metal strip 8' as can best be seen in views C and D. In theconstruction of any curtainwall by the method of this invention, it isoptional whether small or large tucks are employed. The essentialcriterion is that sufficient total overlap be provided to incorporatethe required amount of excess material in the curtainwall to accommodatethe maximum amount of thermal expansion and contraction which may occurin any direction. The total overlapping needed will vary for differentmaterials, for various thicknesses of sheet metal strip, and fordifferent dimensions of individual curtainwalls.

According to the architects choice, the use of more excess material and,thus, more overlapping may be provided than is strictly necessary toaccomodate expansion and contraction. Thus, relatively large tucks mightbe specified and no further wrinkling of the sheet metal strip would berequired to eliminate smooth areas of the sheet metal strip after itsedges had been fastened to the rows of supporting means.

On the other hand, another architect might specify that the minimumamount of material should be used, therefore calling for lessoverlapping and smaller tucks which might not extend very far from theedges of the sheet metal strip toward its longitudinal mid-line.

This is the situation illustrated in FIG. 6, of which view A shows tworows of supporting means 12 and 12' fastened to an underlying buildingstructure and shows strip 8' fastened across these rows of supportingmeans 12 and 12'. In view B of FIG. 6, small tucks 13 have been formedat intervals along both edges of strip 8. View C of FIG. 6 shows howsmall tucks 13 as well as straight portions of the edges of strip 8 havebeen bent over rows of supporting means 12 and 12' so that the edges ofstrip 8' can be fastened thereto by nails 14.

Referring still to FIG. 6, view D illustrates an additional stepcomprising wrinkling of smooth areas of strip 8' which remainundisturbed after the small tucks shown in view B have been fasteneddown as shown in view C. Such wrinkling may be accomplished by hammering(as illustrated) or by other means such as embossing a design into thesurface of strip 8 as shown in FIG. 13.

It should be noted that views A-C in FIG. 5 and views A-D in FIG. 6 donot directly correspond to the similarly lettered method steps appearingin some of the claims. In fact, view A of FIG. 5 as well as view A ofFIG. 6 combine two distinct method steps, namely: (A) attaching twospaced-apart rows of supporting means to an underlying buildingstructure, and (B) fastening a portion of a long sheet metal stripacross said rows of supporting means with the major portion of the widthof said strip spanning the distance between said rows.

Turning now to FIG. 7, a curtainwall constructed according to the methodof this invention is illustrated as it appears when completed, showingsuflicient wrinkling of the sheet metal strip 8 to eliminate all largesmooth areas.

FIGURE 8 illustrates how the curtainwall of this invention may beintegrated with other elements of a building structure. Here sheet metalstrip 8 is shown fastened to supporting means 12 and 12 which arefurring strips and are attached to a building stud or column 16 viapurlins and 15. Flashings 17 and 17' provide the weathe'rproofingnecessary to integrate the curtainwall with the overhang 18 from abuilt-up roof and with the fascia 19.

A useful method for combining two or more curtainwall spandrelsconstructed according to the method of this invention is illustrated inFIG. 9. Here are shown three rows of supporting means, 12, 12', and 12"arranged directly above one another to support a composite verticalcurtainwall.

Two sheet metal strips 8 and 8 are shown fastened to these three rows ofsupporting means, and the top of a third strip 8 is also shown toillustrate how each component sheet metal strip below the top strip isfastened in the form of the letter S (as viewed when a vertical sectionis taken across the composite curtainwall).

For example, the upper edge of strip 8 runs first behind supportingmeans 12 before being fastened behind it and on top of it by nails 14,while the lower edge of strip 8 runs in front of strip 12" before beingfastened beneath and behind it by nails 14. Similarly, the upper edge ofsheet metal strip 8 is shown running behind supporting means 12". Inlike manner, curtain-wall spandrels can be combined to produce acomposite curtainwall of any desired height using sheet metal strip ofstandard available widths. Caulking should be inserted in the spacebetween each row of supporting means and the upper edge of each sheetmetal strip which runs behind any row of supporting means. Similarly,caulking should be inserted between the upper edge of strip 8 andflashing 17 and between the lower edge of strip 8 and fascia 19 in FIG.8 to complete the weatherproofing.

Referring to FIG. 10, views A, B, C, and D illustrate alternativemodifications of means for fastening sheet metal strip 8 to a row ofsupporting means 12. In view A, fastening is by means of nails 14 whichare driven through the sheet metal strip 8 near its edge and into therear of the supporting means 12 which in this case is a furring strip.It is advantageous to bend a portion of strip 8 over the top of afurring strip and to nail it to the rear side. In this way, almost allof the weight of the curtainwall and the effects of pulling, tugging,hammering, and tuck formation during the construction steps aredistributed over a large area of the supporting means 12 instead ofpulling directly against nails 14 which might tear through the sheetmetal if the strip were nailed to the front side of a furring strip.Nevertheless, Where desirable for other reasons, it is entirely withinthe scope of this invention to nail or otherwise fasten the edge of asheet metal strip directly to the front of a furring strip or othersupporting means.

Similarly, in view B of FIG. 10, one edge of sheet metal strip 8 is bentover supporting means 12 and is fastened between means 12 and channelclamp 20, which is tightened down in compression against the edge ofstrip 8 and supporting means 12 by wing bolts 21. Channel champs likethe example illustrated in view B may be many feet long and are of valuein cases where the curtainwall is not finished on the inside and will besubjected to sea spray or other corrosive conditions which may dictatereplacement at frequent intervals. This modification of a fasteningmeans is also useful for constructing temporary curtainwalls orwindbreaks using very inexpensive thin gauge sheet metal.

View C of FIG. 10 shows still another modification of means forfastening a sheet metal strip 8 to supporting means 12. This case lendsitself to very high speed curtainwall construction and employsindustrial staple guns to drive staples into a furring strip to whichthe sheet metal strip must be fastened. This is probably the leastexpensive and fastest means of fastening a sheet metal strip to asupporting mean.

View D of FIG. 10 shows a stirrup clamp 22 which exerts compressionagainst opposite sides of a supporting means 12 such as the furringstrip illustrated and holds the edge of a sheet metal strip tightlybetween itself and the furring strip.

Referring now to FIG. 11, view A illustrates two rows of spaced-apartsupporting means 12 and 12' which have been attached to an underlyingbuilding structure 5 and across which one end of a precreased sheetmetal strip 23 has been fastened. Accordion folds 24 and 25 formpredetermined starting points for overlapping portions of the sheetmetal to form tucks 26 which may be seen in view B of FIG. 11. Thesetucks may comprise any desired amount of overlap using the preformedcrease as a starting point. View C of FIG. 11 shows how the completedcurtainwall made from precreased sheet metal looks like the curtainwallof FIG. 7. Again, according to whether the architect called for small orlarge tucks, additional wrinkling to remove smooth areas of the surfaceof strip 23 which might remain undisturbed after tuck formation may ormay not be necessary as previously discussed.

Referring now to FIG. 12, two vertical, spaced-apart supporting means 12and 12 are attached to an underlying building structure (not shown) anda strip of sheet metal 8 uncoiling from roll 27, which is carried byhoisting truss 28, has been employed to construct a curtainwallaccording to the method of this invention. Tucks 13 were formed aspreviously discussed while continuing the fastening of the edges ofstrip 8 to supporting means 12 and 12.

FIGURE 13 illustrates an embossing die 29 having a design 30 which maycomprise either raised or depressed areas held behind a portion of thesheet metal surface 31 of the curtainwall of this invention while ahammer 32 is used to beat the design 30 into the surface 31 of thecurtainwall.

DESCRIPTION OF THE PREFERRED EMBODIMENT In one example of a preferredembodiment of this invention, the sheet metal strip employed inconstructing the curtainwalls comprising the outer skin of a largeofiice building recently completed in Richmond, Va., was 0.032 inchthick natural aluminum sheet. This aluminum strip was supplied by themanufacturer in coils 9 feet wide by 700 feet long. This length wasespecially suited to the size of the building which "was circular with amaximum circumference of about 700 feet. Thus, the 700 foot lengthssupplied in the coils provided continuous circumferential spandrelsneeding no expansion joints or seams other than one at the starting (andfinishing) point for each spandrel.

In order to provide natural, soft aluminum sheet which would be easy tofold and bend to make tucks, the sheet aluminum coils or rolls wereannealed in an oven until zero temper was obtained. As has beenpreviously discussed, the sheet metal gains in hardness and increasingtemper during hammering and working. The aluminum sheet became quitestiff during the construction of the curtainwalls for the oflicebuilding mentioned above.

Such aluminum strip in various widths is readily available in severalthicknesses and forms a beautiful curtainwall which is very resistant toweathering and surface staining and which does not require anyprotective coating.

Many other types of sheet metal can be employed in strip form toconstruct curtainwalls according to the method of this invention. Forexample, a residence currently under construction in Richmond, Va.,comprises a 3 foot wide exterior curtainwall made from thin ounce coppersheet. This copper sheet will soon form an attractive green carbonatesurface which resists further weathering and, in the wrinkled or rippledform of surface characteristic of curtainwalls made according to themethod of this invention (when not embossed with specific designs) willsoon resemble a mossy stone wall.

Soft stainless steel now sold by Crucible Steel Company under thetrademark Rezistal can be bent and folded easily to form tucks and canbe wrinkled, rippled, or embossed. This material is presently underconsideration for the construction of the curtainwalls of this inventionand probably will be adopted since its cost is about half as much ascopper sheet in equivalent thicknesses.

In the example of a preferred embodiment of this invention mentionedabove, where 0.032 inch thick aluminum strip 9 feet wide was used, thetwo spaced-apart rows of supporting means 12 and 12' took the form of 2inch by 4 inch wooden furring strips which were bolted to the steelframework of the building with a distance of 7 feet 9 inches, measuredbetween their outer edges. Thus, 7 feet 9 inches was the width spannedby the aluminum strip. Tucks were made along both edges of this aluminumstrip at irregular intervals following the general standard devised bythe architect of about 1 inch of overlap per running foot ofcurtainwall. These were relatively small tucks, a typical example beinga 4 inch overlap made after fastening 4 running feet of strip to afurring strip. Wrinkling of the surface of the aluminum strip wascarried out concommitantly with tuck formation and fastening of theedges of the strip to the furring strips. No large smooth areas of thesheet metal surface remained unwrinkled after this process wascompleted. For purposes of illustration only, a smooth, undisturbed areaof more than nine square feet would have been considered too large toleave unwrinkled or unindentated in the example of a preferredembodiment given, where the width of curtainwall was close to 8 feet.

Although applicant is the architect-inventor who conceived this methodfor fabricating light-weight jointless and seamless curtainwalls, thenature of his first project (the office building mentioned above) wasstill so experimental that cost savings available from this inexpensivemethod of curtainwall construction cannot be calculated precisely. Thecost of the aluminum strip employed in the example given was 22 centsper square foot for the 0.032 inch thickness. Considering all othercosts involved, and estimating that the present attainable con structionrate per running foot of an 8 foot wide curtainwall would be double the2 feet per minute speed already attained in practice, it appears thatsuch curtainwalls can be built using the method of this invention at acost total of approximately three times the cost of the sheet metalstrip.

I claim:

1. A curtainwall comprising two spaced-apart rows of supporting meansattached to an underlying building structure and sheet metal stripfastened across said rows of supporting means with the major portion ofthe width of said strip spanning the distance between said rows, withoverlaps at a plurality of points along each edge of said strip wheresaid strip is fastened across said rows of supporting means, therebyincorporating at least sufficient excess metal per linear foot ofcurtainwall to accommodate environmental expansion and contractionwithout the need for expansion joints in said curtainwall, and anembossed pattern in said strip intermediate said rows of supportingmeans.

2. The curtainwall of claim 1 wherein said supporting means are wirecables.

3. The curtainwall of claim 1 wherein said supporting means are furringstrips.

4. The curtainwall of claim 1 wherein said supporting means are lines ofspaced-apart brackets.

5. A composite curtainwall constructed in at least two tiers comprisingat least first, second, and third spacedapart rows of supporting meansattached to an underlying building structure, with a sheet metal stripfastened across each consecutive pair of rows with the major portion ofthe width of each strip spanning the distance between a consecutive pairof rows, with overlaps at a plurality of points near each edge of andalong the length of each strip where said strip is fastened to saidsupporting means, and with each consecutive edge of a strip lapped firstin front of and then behind each row of supporting means in that orderstarting with said second row.

-6. The curtainwall of claim 1 wherein said supporting means are wirecables.

7. The curtainwall of claim 1 wherein said supporting means are lines ofspaced-apart brackets.

8. The curtainwall of claim 5 wherein said supporting means are furringstrips.

9. The curtainwall of claim 5 wherein each sheet metal 1 1 12 strip isem b0ssed intermediate a consecutive pair of rows 3,185,207 5/ 1965Humble 160-348 X of PP means- 3,380,214 4/ 1968 Stevens 52545 ReferencesCited JOHN E. MURTAGH, Primary Examiner UNITED STATES PATENTS 5 US Cl XR520,137 5/1894 De Slauriers 52741X 1,150,594 8/1915 Hale 52-50s X52235,478, 4 508, 573 3,181,597 5/1965 Levine 160348

